Split uos module into os and storage.

os is a subset of CPython's os. storage contains additional
file system mounting functionality based on UNIX's mount
management.

Fixes #140

17 files changed, 851 insertions, 219 deletions

diff --git a/atmel-samd/Makefile b/atmel-samd/Makefile
index 43312fc56..239c80189 100644
--- a/atmel-samd/Makefile
+++ b/atmel-samd/Makefile
@@ -187,7 +187,6 @@ SRC_C = \
 	fatfs_port.c \
 	flash_api.c \
 	main.c \
-	moduos.c \
 	mphalport.c \
 	samd21_pins.c \
 	shared_dma.c \
@@ -228,25 +227,26 @@ STM_SRC_C = $(addprefix stmhal/,\
 	)
 
 SRC_COMMON_HAL = \
-	board/__init__.c \
-	microcontroller/__init__.c \
-	microcontroller/Pin.c \
 	analogio/__init__.c \
 	analogio/AnalogIn.c \
 	analogio/AnalogOut.c \
 	audioio/__init__.c \
 	audioio/AudioOut.c \
+	board/__init__.c \
+	busio/__init__.c \
+	busio/I2C.c \
+	busio/SPI.c \
+	busio/UART.c \
 	digitalio/__init__.c \
 	digitalio/DigitalInOut.c \
+	microcontroller/__init__.c \
+	microcontroller/Pin.c \
+	neopixel_write/__init__.c \
+	os/__init__.c \
 	pulseio/__init__.c \
 	pulseio/PulseIn.c \
 	pulseio/PulseOut.c \
 	pulseio/PWMOut.c \
-	busio/__init__.c \
-	busio/I2C.c \
-	busio/SPI.c \
-	busio/UART.c \
-	neopixel_write/__init__.c \
 	time/__init__.c \
 	touchio/__init__.c \
 	touchio/TouchIn.c \
@@ -271,6 +271,8 @@ SRC_SHARED_MODULE = \
 	bitbangio/OneWire.c \
 	bitbangio/SPI.c \
 	busio/OneWire.c \
+	os/__init__.c \
+	storage/__init__.c \
 	uheap/__init__.c \
 
 SRC_SHARED_MODULE_EXPANDED = $(addprefix shared-bindings/, $(SRC_SHARED_MODULE)) \
diff --git a/atmel-samd/common-hal/os/__init__.c b/atmel-samd/common-hal/os/__init__.c
new file mode 100644
index 000000000..2d2067ee0
--- /dev/null
+++ b/atmel-samd/common-hal/os/__init__.c
@@ -0,0 +1,57 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2017 Scott Shawcroft for Adafruit Industries
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "genhdr/mpversion.h"
+#include "py/mpconfig.h"
+#include "py/objstr.h"
+#include "py/objtuple.h"
+#include "py/qstr.h"
+
+STATIC const qstr os_uname_info_fields[] = {
+    MP_QSTR_sysname, MP_QSTR_nodename,
+    MP_QSTR_release, MP_QSTR_version, MP_QSTR_machine
+};
+STATIC const MP_DEFINE_STR_OBJ(os_uname_info_sysname_obj, "samd21");
+STATIC const MP_DEFINE_STR_OBJ(os_uname_info_nodename_obj, "samd21");
+STATIC const MP_DEFINE_STR_OBJ(os_uname_info_release_obj, MICROPY_VERSION_STRING);
+STATIC const MP_DEFINE_STR_OBJ(os_uname_info_version_obj, MICROPY_GIT_TAG " on " MICROPY_BUILD_DATE);
+STATIC const MP_DEFINE_STR_OBJ(os_uname_info_machine_obj, MICROPY_HW_BOARD_NAME " with " MICROPY_HW_MCU_NAME);
+
+
+STATIC MP_DEFINE_ATTRTUPLE(
+    os_uname_info_obj,
+    os_uname_info_fields,
+    5,
+    (mp_obj_t)&os_uname_info_sysname_obj,
+    (mp_obj_t)&os_uname_info_nodename_obj,
+    (mp_obj_t)&os_uname_info_release_obj,
+    (mp_obj_t)&os_uname_info_version_obj,
+    (mp_obj_t)&os_uname_info_machine_obj
+);
+
+mp_obj_t common_hal_os_uname(void) {
+    return (mp_obj_t)&os_uname_info_obj;
+}
diff --git a/atmel-samd/moduos.c b/atmel-samd/moduos.c
deleted file mode 100644
index cdc6325f2..000000000
--- a/atmel-samd/moduos.c
+++ /dev/null
@@ -1,122 +0,0 @@
-/*
- * This file is part of the Micro Python project, http://micropython.org/
- *
- * The MIT License (MIT)
- *
- * Copyright (c) 2013, 2014 Damien P. George
- *
- * Permission is hereby granted, free of charge, to any person obtaining a copy
- * of this software and associated documentation files (the "Software"), to deal
- * in the Software without restriction, including without limitation the rights
- * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
- * copies of the Software, and to permit persons to whom the Software is
- * furnished to do so, subject to the following conditions:
- *
- * The above copyright notice and this permission notice shall be included in
- * all copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
- * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
- * THE SOFTWARE.
- */
-
-#include <stdint.h>
-#include <string.h>
-
-#include "py/mpstate.h"
-#include "py/objtuple.h"
-#include "py/objstr.h"
-#include "py/runtime.h"
-#include "genhdr/mpversion.h"
-#include "lib/oofatfs/ff.h"
-#include "lib/oofatfs/diskio.h"
-#include "extmod/vfs.h"
-#include "extmod/vfs_fat.h"
-#include "timeutils.h"
-
-/// \module os - basic "operating system" services
-///
-/// The `os` module contains functions for filesystem access and `urandom`.
-///
-/// The filesystem has `/` as the root directory, and the available physical
-/// drives are accessible from here.  They are currently:
-///
-///     /flash      -- the internal flash filesystem
-///     /sd         -- the SD card (if it exists)
-///
-/// On boot up, the current directory is `/flash` if no SD card is inserted,
-/// otherwise it is `/sd`.
-
-STATIC const qstr os_uname_info_fields[] = {
-    MP_QSTR_sysname, MP_QSTR_nodename,
-    MP_QSTR_release, MP_QSTR_version, MP_QSTR_machine
-};
-STATIC const MP_DEFINE_STR_OBJ(os_uname_info_sysname_obj, "samd21");
-STATIC const MP_DEFINE_STR_OBJ(os_uname_info_nodename_obj, "samd21");
-STATIC const MP_DEFINE_STR_OBJ(os_uname_info_release_obj, MICROPY_VERSION_STRING);
-STATIC const MP_DEFINE_STR_OBJ(os_uname_info_version_obj, MICROPY_GIT_TAG " on " MICROPY_BUILD_DATE);
-STATIC const MP_DEFINE_STR_OBJ(os_uname_info_machine_obj, MICROPY_HW_BOARD_NAME " with " MICROPY_HW_MCU_NAME);
-STATIC MP_DEFINE_ATTRTUPLE(
-    os_uname_info_obj,
-    os_uname_info_fields,
-    5,
-    (mp_obj_t)&os_uname_info_sysname_obj,
-    (mp_obj_t)&os_uname_info_nodename_obj,
-    (mp_obj_t)&os_uname_info_release_obj,
-    (mp_obj_t)&os_uname_info_version_obj,
-    (mp_obj_t)&os_uname_info_machine_obj
-);
-
-STATIC mp_obj_t os_uname(void) {
-    return (mp_obj_t)&os_uname_info_obj;
-}
-STATIC MP_DEFINE_CONST_FUN_OBJ_0(os_uname_obj, os_uname);
-
-/// \function sync()
-/// Sync all filesystems.
-STATIC mp_obj_t os_sync(void) {
-    for (mp_vfs_mount_t *vfs = MP_STATE_VM(vfs_mount_table); vfs != NULL; vfs = vfs->next) {
-        // this assumes that vfs->obj is fs_user_mount_t with block device functions
-        disk_ioctl(MP_OBJ_TO_PTR(vfs->obj), CTRL_SYNC, NULL);
-    }
-    return mp_const_none;
-}
-MP_DEFINE_CONST_FUN_OBJ_0(mod_os_sync_obj, os_sync);
-
-STATIC const mp_rom_map_elem_t os_module_globals_table[] = {
-    { MP_OBJ_NEW_QSTR(MP_QSTR___name__), MP_OBJ_NEW_QSTR(MP_QSTR_uos) },
-
-    { MP_OBJ_NEW_QSTR(MP_QSTR_uname), MP_ROM_PTR(&os_uname_obj) },
-
-    { MP_OBJ_NEW_QSTR(MP_QSTR_chdir), MP_ROM_PTR(&mp_vfs_chdir_obj) },
-    { MP_OBJ_NEW_QSTR(MP_QSTR_getcwd), MP_ROM_PTR(&mp_vfs_getcwd_obj) },
-    { MP_OBJ_NEW_QSTR(MP_QSTR_listdir), MP_ROM_PTR(&mp_vfs_listdir_obj) },
-    { MP_OBJ_NEW_QSTR(MP_QSTR_mkdir), MP_ROM_PTR(&mp_vfs_mkdir_obj) },
-    { MP_OBJ_NEW_QSTR(MP_QSTR_remove), MP_ROM_PTR(&mp_vfs_remove_obj) },
-    { MP_OBJ_NEW_QSTR(MP_QSTR_rename), MP_ROM_PTR(&mp_vfs_rename_obj) },
-    { MP_OBJ_NEW_QSTR(MP_QSTR_rmdir), MP_ROM_PTR(&mp_vfs_rmdir_obj) },
-    { MP_OBJ_NEW_QSTR(MP_QSTR_stat), MP_ROM_PTR(&mp_vfs_stat_obj) },
-    { MP_OBJ_NEW_QSTR(MP_QSTR_statvfs), MP_ROM_PTR(&mp_vfs_statvfs_obj) },
-    { MP_OBJ_NEW_QSTR(MP_QSTR_unlink), MP_ROM_PTR(&mp_vfs_remove_obj) }, // unlink aliases to remove
-
-    { MP_OBJ_NEW_QSTR(MP_QSTR_sync), MP_ROM_PTR(&mod_os_sync_obj) },
-
-    /// \constant sep - separation character used in paths
-    { MP_OBJ_NEW_QSTR(MP_QSTR_sep), MP_OBJ_NEW_QSTR(MP_QSTR__slash_) },
-
-    // these are MicroPython extensions
-    { MP_OBJ_NEW_QSTR(MP_QSTR_mount), MP_ROM_PTR(&mp_vfs_mount_obj) },
-    { MP_OBJ_NEW_QSTR(MP_QSTR_umount), MP_ROM_PTR(&mp_vfs_umount_obj) },
-    { MP_OBJ_NEW_QSTR(MP_QSTR_VfsFat), MP_ROM_PTR(&mp_fat_vfs_type) },
-};
-
-STATIC MP_DEFINE_CONST_DICT(os_module_globals, os_module_globals_table);
-
-const mp_obj_module_t uos_module = {
-    .base = { &mp_type_module },
-    .globals = (mp_obj_dict_t*)&os_module_globals,
-};
diff --git a/atmel-samd/mpconfigport.h b/atmel-samd/mpconfigport.h
index b6175edb9..06e789ed1 100644
--- a/atmel-samd/mpconfigport.h
+++ b/atmel-samd/mpconfigport.h
@@ -137,7 +137,8 @@ extern const struct _mp_obj_module_t digitalio_module;
 extern const struct _mp_obj_module_t pulseio_module;
 extern const struct _mp_obj_module_t busio_module;
 extern const struct _mp_obj_module_t board_module;
-extern const struct _mp_obj_module_t uos_module;
+extern const struct _mp_obj_module_t os_module;
+extern const struct _mp_obj_module_t storage_module;
 extern const struct _mp_obj_module_t time_module;
 extern const struct _mp_obj_module_t neopixel_write_module;
 extern const struct _mp_obj_module_t uheap_module;
@@ -174,7 +175,8 @@ extern const struct _mp_obj_module_t usb_hid_module;
     { MP_OBJ_NEW_QSTR(MP_QSTR_digitalio), (mp_obj_t)&digitalio_module }, \
     { MP_OBJ_NEW_QSTR(MP_QSTR_busio), (mp_obj_t)&busio_module }, \
     { MP_OBJ_NEW_QSTR(MP_QSTR_board), (mp_obj_t)&board_module }, \
-    { MP_OBJ_NEW_QSTR(MP_QSTR_uos), (mp_obj_t)&uos_module }, \
+    { MP_OBJ_NEW_QSTR(MP_QSTR_os), (mp_obj_t)&os_module }, \
+    { MP_OBJ_NEW_QSTR(MP_QSTR_storage), (mp_obj_t)&storage_module }, \
     { MP_OBJ_NEW_QSTR(MP_QSTR_time), (mp_obj_t)&time_module }, \
     { MP_OBJ_NEW_QSTR(MP_QSTR_neopixel_write),(mp_obj_t)&neopixel_write_module }, \
     { MP_OBJ_NEW_QSTR(MP_QSTR_samd),(mp_obj_t)&samd_module }, \
diff --git a/docs/README.md b/docs/README.md
index 6e7925811..9b188a98a 100644
--- a/docs/README.md
+++ b/docs/README.md
@@ -1,11 +1,11 @@
-Adafruit's MicroPython Documentation
+Adafruit's CircuitPython Documentation
 =========================
 
 The latest documentation can be found at:
-http://adafruit-micropython.readthedocs.io/en/latest/
+http://circuitpython.readthedocs.io/en/latest/
 
 The documentation you see there is generated from the files in the whole tree:
-https://github.com/adafruit/micropython/tree/master
+https://github.com/adafruit/circuitpython/tree/master
 
 Building the documentation locally
 ----------------------------------
@@ -19,8 +19,8 @@ preferably in a virtualenv:
      pip install sphinx
      pip install sphinx_rtd_theme
 
-In `micropython/`, build the docs:
+In `circuitpython/`, build the docs:
 
     sphinx-build -v -b html . _build/html
 
-You'll find the index page at `micropython/docs/_build/html/index.html`.
+You'll find the index page at `_build/html/index.html`.
diff --git a/esp8266/Makefile b/esp8266/Makefile
index c1ec3ca93..54c826351 100644
--- a/esp8266/Makefile
+++ b/esp8266/Makefile
@@ -93,8 +93,6 @@ SRC_C = \
 	machine_hspi.c \
 	modesp.c \
 	modnetwork.c \
-	modutime.c \
-	moduos.c \
 	modonewire.c \
 	ets_alt_task.c \
 	fatfs_port.c \
@@ -119,6 +117,7 @@ SRC_COMMON_HAL = \
 	busio/SPI.c \
 	busio/UART.c \
 	neopixel_write/__init__.c \
+	os/__init__.c \
 	time/__init__.c \
 	board/__init__.c
 
@@ -139,6 +138,8 @@ SRC_SHARED_MODULE = \
 	bitbangio/SPI.c \
 	busio/I2C.c \
 	busio/OneWire.c \
+	os/__init__.c \
+	storage/__init__.c \
 
 SRC_SHARED_MODULE_EXPANDED = $(addprefix shared-bindings/, $(SRC_SHARED_MODULE)) \
                              $(addprefix shared-module/, $(SRC_SHARED_MODULE))
diff --git a/esp8266/moduos.c b/esp8266/common-hal/os/__init__.c
index 807d2e18a..df241ecae 100644
--- a/esp8266/moduos.c
+++ b/esp8266/common-hal/os/__init__.c
@@ -4,6 +4,7 @@
  * The MIT License (MIT)
  *
  * Copyright (c) 2015 Josef Gajdusek
+ * Copyright (c) 2017 Scott Shawcroft for Adafruit Industries
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -28,11 +29,7 @@
 
 #include "py/objtuple.h"
 #include "py/objstr.h"
-#include "extmod/misc.h"
-#include "extmod/vfs.h"
-#include "extmod/vfs_fat.h"
 #include "genhdr/mpversion.h"
-#include "esp_mphal.h"
 #include "user_interface.h"
 
 STATIC const qstr os_uname_info_fields[] = {
@@ -57,60 +54,9 @@ STATIC mp_obj_tuple_t os_uname_info_obj = {
     }
 };
 
-STATIC mp_obj_t os_uname(void) {
+mp_obj_t common_hal_os_uname(void) {
     // We must populate the "release" field each time in case it was GC'd since the last call.
     const char *ver = system_get_sdk_version();
     os_uname_info_obj.items[2] = mp_obj_new_str(ver, strlen(ver), false);
     return (mp_obj_t)&os_uname_info_obj;
 }
-STATIC MP_DEFINE_CONST_FUN_OBJ_0(os_uname_obj, os_uname);
-
-STATIC mp_obj_t os_urandom(mp_obj_t num) {
-    mp_int_t n = mp_obj_get_int(num);
-    vstr_t vstr;
-    vstr_init_len(&vstr, n);
-    for (int i = 0; i < n; i++) {
-        vstr.buf[i] = *WDEV_HWRNG;
-    }
-    return mp_obj_new_str_from_vstr(&mp_type_bytes, &vstr);
-}
-STATIC MP_DEFINE_CONST_FUN_OBJ_1(os_urandom_obj, os_urandom);
-
-STATIC mp_obj_t os_dupterm_notify(mp_obj_t obj_in) {
-    (void)obj_in;
-    mp_hal_signal_dupterm_input();
-    return mp_const_none;
-}
-STATIC MP_DEFINE_CONST_FUN_OBJ_1(os_dupterm_notify_obj, os_dupterm_notify);
-
-STATIC const mp_rom_map_elem_t os_module_globals_table[] = {
-    { MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_uos) },
-    { MP_ROM_QSTR(MP_QSTR_uname), MP_ROM_PTR(&os_uname_obj) },
-    { MP_ROM_QSTR(MP_QSTR_urandom), MP_ROM_PTR(&os_urandom_obj) },
-    #if MICROPY_PY_OS_DUPTERM
-    { MP_ROM_QSTR(MP_QSTR_dupterm), MP_ROM_PTR(&mp_uos_dupterm_obj) },
-    { MP_ROM_QSTR(MP_QSTR_dupterm_notify), MP_ROM_PTR(&os_dupterm_notify_obj) },
-    #endif
-    #if MICROPY_VFS_FAT
-    { MP_ROM_QSTR(MP_QSTR_VfsFat), MP_ROM_PTR(&mp_fat_vfs_type) },
-    { MP_ROM_QSTR(MP_QSTR_ilistdir), MP_ROM_PTR(&mp_vfs_ilistdir_obj) },
-    { MP_ROM_QSTR(MP_QSTR_listdir), MP_ROM_PTR(&mp_vfs_listdir_obj) },
-    { MP_ROM_QSTR(MP_QSTR_mkdir), MP_ROM_PTR(&mp_vfs_mkdir_obj) },
-    { MP_ROM_QSTR(MP_QSTR_rmdir), MP_ROM_PTR(&mp_vfs_rmdir_obj) },
-    { MP_ROM_QSTR(MP_QSTR_chdir), MP_ROM_PTR(&mp_vfs_chdir_obj) },
-    { MP_ROM_QSTR(MP_QSTR_getcwd), MP_ROM_PTR(&mp_vfs_getcwd_obj) },
-    { MP_ROM_QSTR(MP_QSTR_remove), MP_ROM_PTR(&mp_vfs_remove_obj) },
-    { MP_ROM_QSTR(MP_QSTR_rename), MP_ROM_PTR(&mp_vfs_rename_obj) },
-    { MP_ROM_QSTR(MP_QSTR_stat), MP_ROM_PTR(&mp_vfs_stat_obj) },
-    { MP_ROM_QSTR(MP_QSTR_statvfs), MP_ROM_PTR(&mp_vfs_statvfs_obj) },
-    { MP_ROM_QSTR(MP_QSTR_mount), MP_ROM_PTR(&mp_vfs_mount_obj) },
-    { MP_ROM_QSTR(MP_QSTR_umount), MP_ROM_PTR(&mp_vfs_umount_obj) },
-    #endif
-};
-
-STATIC MP_DEFINE_CONST_DICT(os_module_globals, os_module_globals_table);
-
-const mp_obj_module_t uos_module = {
-    .base = { &mp_type_module },
-    .globals = (mp_obj_dict_t*)&os_module_globals,
-};
diff --git a/esp8266/mpconfigport.h b/esp8266/mpconfigport.h
index fec1eb0f0..066788832 100644
--- a/esp8266/mpconfigport.h
+++ b/esp8266/mpconfigport.h
@@ -156,7 +156,8 @@ void *esp_native_code_commit(void*, size_t);
 extern const struct _mp_obj_module_t esp_module;
 extern const struct _mp_obj_module_t network_module;
 extern const struct _mp_obj_module_t utime_module;
-extern const struct _mp_obj_module_t uos_module;
+extern const struct _mp_obj_module_t os_module;
+extern const struct _mp_obj_module_t storage_module;
 extern const struct _mp_obj_module_t mp_module_lwip;
 extern const struct _mp_obj_module_t mp_module_machine;
 extern const struct _mp_obj_module_t onewire_module;
@@ -174,8 +175,7 @@ extern const struct _mp_obj_module_t time_module;
     { MP_OBJ_NEW_QSTR(MP_QSTR_socket), (mp_obj_t)&mp_module_lwip }, \
     { MP_OBJ_NEW_QSTR(MP_QSTR_usocket), (mp_obj_t)&mp_module_lwip }, \
     { MP_OBJ_NEW_QSTR(MP_QSTR_network), (mp_obj_t)&network_module }, \
-    { MP_OBJ_NEW_QSTR(MP_QSTR_utime), (mp_obj_t)&utime_module }, \
-    { MP_OBJ_NEW_QSTR(MP_QSTR_uos), (mp_obj_t)&uos_module }, \
+    { MP_OBJ_NEW_QSTR(MP_QSTR_os), (mp_obj_t)&os_module }, \
     { MP_OBJ_NEW_QSTR(MP_QSTR_machine), (mp_obj_t)&mp_module_machine }, \
     { MP_OBJ_NEW_QSTR(MP_QSTR__onewire), (mp_obj_t)&onewire_module }, \
     { MP_OBJ_NEW_QSTR(MP_QSTR_microcontroller), (mp_obj_t)&microcontroller_module }, \
@@ -185,10 +185,10 @@ extern const struct _mp_obj_module_t time_module;
     { MP_OBJ_NEW_QSTR(MP_QSTR_pulseio), (mp_obj_t)&pulseio_module }, \
     { MP_OBJ_NEW_QSTR(MP_QSTR_busio), (mp_obj_t)&busio_module }, \
     { MP_OBJ_NEW_QSTR(MP_QSTR_bitbangio), (mp_obj_t)&bitbangio_module }, \
+    { MP_OBJ_NEW_QSTR(MP_QSTR_storage), (mp_obj_t)&storage_module }, \
     { MP_OBJ_NEW_QSTR(MP_QSTR_time), (mp_obj_t)&time_module }, \
 
 #define MICROPY_PORT_BUILTIN_MODULE_WEAK_LINKS \
-    { MP_OBJ_NEW_QSTR(MP_QSTR_os), (mp_obj_t)&uos_module }, \
     { MP_OBJ_NEW_QSTR(MP_QSTR_json), (mp_obj_t)&mp_module_ujson }, \
     { MP_OBJ_NEW_QSTR(MP_QSTR_errno), (mp_obj_t)&mp_module_uerrno }, \
     { MP_OBJ_NEW_QSTR(MP_QSTR_select), (mp_obj_t)&mp_module_uselect }, \
diff --git a/extmod/vfs.c b/extmod/vfs.c
index 3bdce80db..3aa1d7744 100644
--- a/extmod/vfs.c
+++ b/extmod/vfs.c
@@ -289,18 +289,7 @@ mp_obj_t mp_vfs_getcwd(void) {
 }
 MP_DEFINE_CONST_FUN_OBJ_0(mp_vfs_getcwd_obj, mp_vfs_getcwd);
 
-typedef struct _mp_vfs_ilistdir_it_t {
-    mp_obj_base_t base;
-    mp_fun_1_t iternext;
-    union {
-        mp_vfs_mount_t *vfs;
-        mp_obj_t iter;
-    } cur;
-    bool is_str;
-    bool is_iter;
-} mp_vfs_ilistdir_it_t;
-
-STATIC mp_obj_t mp_vfs_ilistdir_it_iternext(mp_obj_t self_in) {
+mp_obj_t mp_vfs_ilistdir_it_iternext(mp_obj_t self_in) {
     mp_vfs_ilistdir_it_t *self = MP_OBJ_TO_PTR(self_in);
     if (self->is_iter) {
         // continue delegating to root dir
diff --git a/extmod/vfs.h b/extmod/vfs.h
index edaeb5349..3302f55f4 100644
--- a/extmod/vfs.h
+++ b/extmod/vfs.h
@@ -53,6 +53,17 @@ typedef struct _mp_vfs_mount_t {
     struct _mp_vfs_mount_t *next;
 } mp_vfs_mount_t;
 
+typedef struct _mp_vfs_ilistdir_it_t {
+    mp_obj_base_t base;
+    mp_fun_1_t iternext;
+    union {
+        mp_vfs_mount_t *vfs;
+        mp_obj_t iter;
+    } cur;
+    bool is_str;
+    bool is_iter;
+} mp_vfs_ilistdir_it_t;
+
 mp_vfs_mount_t *mp_vfs_lookup_path(const char *path, const char **path_out);
 mp_import_stat_t mp_vfs_import_stat(const char *path);
 mp_obj_t mp_vfs_mount(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args);
@@ -69,6 +80,8 @@ mp_obj_t mp_vfs_rmdir(mp_obj_t path_in);
 mp_obj_t mp_vfs_stat(mp_obj_t path_in);
 mp_obj_t mp_vfs_statvfs(mp_obj_t path_in);
 
+mp_obj_t mp_vfs_ilistdir_it_iternext(mp_obj_t self_in);
+
 MP_DECLARE_CONST_FUN_OBJ_KW(mp_vfs_mount_obj);
 MP_DECLARE_CONST_FUN_OBJ_1(mp_vfs_umount_obj);
 MP_DECLARE_CONST_FUN_OBJ_KW(mp_vfs_open_obj);
diff --git a/shared-bindings/index.rst b/shared-bindings/index.rst
index e44c60f83..918fb5675 100644
--- a/shared-bindings/index.rst
+++ b/shared-bindings/index.rst
@@ -12,13 +12,13 @@ limited. For example, a microcontroller without analog features will not have
 Support Matrix
 ---------------
 
-===============  ==========  =========  ===========  =======  =======  ===========  =================  ================  =========  ========  =========  =======  =========
-Port             `analogio`  `audioio`  `bitbangio`  `board`  `busio`  `digitalio`  `microcontroller`  `neopixel_write`  `pulseio`  `time`    `touchio`  `uheap`  `usb_hid`
-===============  ==========  =========  ===========  =======  =======  ===========  =================  ================  =========  ========  =========  =======  =========
-SAMD21           **Yes**     No         No           **Yes**  **Yes**  **Yes**      **Yes**            **Yes**           No         **Yes**   **Yes**    Debug    **Yes**
-SAMD21 Express   **Yes**     **Yes**    **Yes**      **Yes**  **Yes**  **Yes**      **Yes**            **Yes**           **Yes**    **Yes**   **Yes**    Debug    **Yes**
-ESP8266          **Yes**     No         **Yes**      **Yes**  **Yes**  **Yes**      **Yes**            **Yes**           No         **Yes**   No         Debug    No
-===============  ==========  =========  ===========  =======  =======  ===========  =================  ================  =========  ========  =========  =======  =========
+===============  ==========  =========  ===========  =======  =======  ===========  =================  ================  =======  =========  =========  ========  =========  =======  =========
+Port             `analogio`  `audioio`  `bitbangio`  `board`  `busio`  `digitalio`  `microcontroller`  `neopixel_write`  `os`     `pulseio`  `storage`  `time`    `touchio`  `uheap`  `usb_hid`
+===============  ==========  =========  ===========  =======  =======  ===========  =================  ================  =======  =========  =========  ========  =========  =======  =========
+SAMD21           **Yes**     No         No           **Yes**  **Yes**  **Yes**      **Yes**            **Yes**           **Yes**  No         **Yes**    **Yes**   **Yes**    Debug    **Yes**
+SAMD21 Express   **Yes**     **Yes**    **Yes**      **Yes**  **Yes**  **Yes**      **Yes**            **Yes**           **Yes**  **Yes**    **Yes**    **Yes**   **Yes**    Debug    **Yes**
+ESP8266          **Yes**     No         **Yes**      **Yes**  **Yes**  **Yes**      **Yes**            **Yes**           **Yes**  No         **Yes**    **Yes**   No         Debug    No
+===============  ==========  =========  ===========  =======  =======  ===========  =================  ================  =======  =========  =========  ========  =========  =======  =========
 
 Modules
 ---------
diff --git a/shared-bindings/os/__init__.c b/shared-bindings/os/__init__.c
new file mode 100644
index 000000000..6185f0bf2
--- /dev/null
+++ b/shared-bindings/os/__init__.c
@@ -0,0 +1,221 @@
+/*
+ * This file is part of the Micro Python project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2013, 2014 Damien P. George
+ * Copyright (c) 2015 Josef Gajdusek
+ * Copyright (c) 2016 Scott Shawcroft for Adafruit Industries
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include <string.h>
+
+#include "extmod/vfs.h"
+#include "lib/oofatfs/ff.h"
+#include "lib/oofatfs/diskio.h"
+#include "py/mpstate.h"
+#include "py/obj.h"
+#include "shared-bindings/os/__init__.h"
+
+//| :mod:`os` --- functions that an OS normally provides
+//| ========================================================
+//|
+//| .. module:: os
+//|   :synopsis: functions that an OS normally provides
+//|   :platform: SAMD21
+//|
+//| The `os` module is a strict subset of the CPython `cpython:os` module. So,
+//| code written in CircuitPython will work in CPython but not necessarily the
+//| other way around.
+//|
+
+//| .. function:: uname()
+//|
+//|   Returns a named tuple of operating specific and CircuitPython port
+//|   specific information.
+//|
+STATIC mp_obj_t os_uname(void) {
+    return common_hal_os_uname();
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_0(os_uname_obj, os_uname);
+
+//| .. function:: chdir(path)
+//|
+//|   Change current directory.
+//|
+mp_obj_t os_chdir(mp_obj_t path_in) {
+    const char *path = mp_obj_str_get_str(path_in);
+    common_hal_os_chdir(path);
+    return mp_const_none;
+}
+MP_DEFINE_CONST_FUN_OBJ_1(os_chdir_obj, os_chdir);
+
+//| .. function:: getcwd()
+//|
+//|   Get the current directory.
+//|
+mp_obj_t os_getcwd(void) {
+    return common_hal_os_getcwd();
+}
+MP_DEFINE_CONST_FUN_OBJ_0(os_getcwd_obj, os_getcwd);
+
+//| .. function:: listdir([dir])
+//|
+//|   With no argument, list the current directory.  Otherwise list the given directory.
+//|
+mp_obj_t os_listdir(size_t n_args, const mp_obj_t *args) {
+    const char* path;
+    if (n_args == 1) {
+        path = mp_obj_str_get_str(args[0]);
+    } else {
+        path = "";
+    }
+    return common_hal_os_listdir(path);
+}
+MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(os_listdir_obj, 0, 1, os_listdir);
+
+//| .. function:: mkdir(path)
+//|
+//|   Create a new directory.
+//|
+mp_obj_t os_mkdir(mp_obj_t path_in) {
+    const char *path = mp_obj_str_get_str(path_in);
+    common_hal_os_mkdir(path);
+    return mp_const_none;
+}
+MP_DEFINE_CONST_FUN_OBJ_1(os_mkdir_obj, os_mkdir);
+
+//| .. function:: remove(path)
+//|
+//|   Remove a file.
+//|
+mp_obj_t os_remove(mp_obj_t path_in) {
+    const char *path = mp_obj_str_get_str(path_in);
+    common_hal_os_remove(path);
+    return mp_const_none;
+}
+MP_DEFINE_CONST_FUN_OBJ_1(os_remove_obj, os_remove);
+
+//| .. function:: rmdir(path)
+//|
+//|   Remove a directory.
+//|
+mp_obj_t os_rename(mp_obj_t old_path_in, mp_obj_t new_path_in) {
+    const char *old_path = mp_obj_str_get_str(old_path_in);
+    const char *new_path = mp_obj_str_get_str(new_path_in);
+    common_hal_os_rename(old_path, new_path);
+    return mp_const_none;
+}
+MP_DEFINE_CONST_FUN_OBJ_2(os_rename_obj, os_rename);
+
+//| .. function:: rename(old_path, new_path)
+//|
+//|   Rename a file.
+//|
+mp_obj_t os_rmdir(mp_obj_t path_in) {
+    const char *path = mp_obj_str_get_str(path_in);
+    common_hal_os_rmdir(path);
+    return mp_const_none;
+}
+MP_DEFINE_CONST_FUN_OBJ_1(os_rmdir_obj, os_rmdir);
+
+//| .. function:: stat(path)
+//|
+//|   Get the status of a file or directory.
+//|
+mp_obj_t os_stat(mp_obj_t path_in) {
+    const char *path = mp_obj_str_get_str(path_in);
+    return common_hal_os_stat(path);
+}
+MP_DEFINE_CONST_FUN_OBJ_1(os_stat_obj, os_stat);
+
+//| .. function:: statvfs(path)
+//|
+//|   Get the status of a fileystem.
+//|
+//|   Returns a tuple with the filesystem information in the following order:
+//|
+//|        * ``f_bsize`` -- file system block size
+//|        * ``f_frsize`` -- fragment size
+//|        * ``f_blocks`` -- size of fs in f_frsize units
+//|        * ``f_bfree`` -- number of free blocks
+//|        * ``f_bavail`` -- number of free blocks for unpriviliged users
+//|        * ``f_files`` -- number of inodes
+//|        * ``f_ffree`` -- number of free inodes
+//|        * ``f_favail`` -- number of free inodes for unpriviliged users
+//|        * ``f_flag`` -- mount flags
+//|        * ``f_namemax`` -- maximum filename length
+//|
+//|   Parameters related to inodes: ``f_files``, ``f_ffree``, ``f_avail``
+//|   and the ``f_flags`` parameter may return ``0`` as they can be unavailable
+//|   in a port-specific implementation.
+//|
+mp_obj_t os_statvfs(mp_obj_t path_in) {
+    const char *path = mp_obj_str_get_str(path_in);
+    return common_hal_os_statvfs(path);
+}
+MP_DEFINE_CONST_FUN_OBJ_1(os_statvfs_obj, os_statvfs);
+
+//| .. function:: sync()
+//|
+//|   Sync all filesystems.
+//|
+STATIC mp_obj_t os_sync(void) {
+    for (mp_vfs_mount_t *vfs = MP_STATE_VM(vfs_mount_table); vfs != NULL; vfs = vfs->next) {
+        // this assumes that vfs->obj is fs_user_mount_t with block device functions
+        disk_ioctl(MP_OBJ_TO_PTR(vfs->obj), CTRL_SYNC, NULL);
+    }
+    return mp_const_none;
+}
+MP_DEFINE_CONST_FUN_OBJ_0(os_sync_obj, os_sync);
+
+
+STATIC const mp_rom_map_elem_t os_module_globals_table[] = {
+    { MP_OBJ_NEW_QSTR(MP_QSTR___name__), MP_OBJ_NEW_QSTR(MP_QSTR_os) },
+
+    { MP_OBJ_NEW_QSTR(MP_QSTR_uname), MP_ROM_PTR(&os_uname_obj) },
+
+    { MP_OBJ_NEW_QSTR(MP_QSTR_chdir), MP_ROM_PTR(&os_chdir_obj) },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_getcwd), MP_ROM_PTR(&os_getcwd_obj) },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_listdir), MP_ROM_PTR(&os_listdir_obj) },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_mkdir), MP_ROM_PTR(&os_mkdir_obj) },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_remove), MP_ROM_PTR(&os_remove_obj) },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_rename), MP_ROM_PTR(&os_rename_obj) },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_rmdir), MP_ROM_PTR(&os_rmdir_obj) },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_stat), MP_ROM_PTR(&os_stat_obj) },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_statvfs), MP_ROM_PTR(&os_statvfs_obj) },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_unlink), MP_ROM_PTR(&os_remove_obj) }, // unlink aliases to remove
+
+    { MP_OBJ_NEW_QSTR(MP_QSTR_sync), MP_ROM_PTR(&os_sync_obj) },
+
+//| .. data:: sep
+//|
+//|   Separator used to dileneate path components such as folder and file names.
+//|
+    { MP_OBJ_NEW_QSTR(MP_QSTR_sep), MP_OBJ_NEW_QSTR(MP_QSTR__slash_) },
+};
+
+STATIC MP_DEFINE_CONST_DICT(os_module_globals, os_module_globals_table);
+
+const mp_obj_module_t os_module = {
+    .base = { &mp_type_module },
+    .globals = (mp_obj_dict_t*)&os_module_globals,
+};
diff --git a/shared-bindings/os/__init__.h b/shared-bindings/os/__init__.h
new file mode 100644
index 000000000..e04a39319
--- /dev/null
+++ b/shared-bindings/os/__init__.h
@@ -0,0 +1,48 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2016 Scott Shawcroft for Adafruit Industries
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#ifndef __MICROPY_INCLUDED_SHARED_BINDINGS_OS___INIT___H__
+#define __MICROPY_INCLUDED_SHARED_BINDINGS_OS___INIT___H__
+
+#include <stdint.h>
+#include <stdbool.h>
+
+#include "py/objtuple.h"
+
+const mp_rom_obj_tuple_t common_hal_os_uname_info_obj;
+
+mp_obj_t common_hal_os_uname(void);
+void common_hal_os_chdir(const char* path);
+mp_obj_t common_hal_os_getcwd(void);
+mp_obj_t common_hal_os_listdir(const char* path);
+void common_hal_os_mkdir(const char* path);
+void common_hal_os_remove(const char* path);
+void common_hal_os_rename(const char* old_path, const char* new_path);
+void common_hal_os_rmdir(const char* path);
+mp_obj_t common_hal_os_stat(const char* path);
+mp_obj_t common_hal_os_statvfs(const char* path);
+
+#endif  // __MICROPY_INCLUDED_SHARED_BINDINGS_OS___INIT___H__
diff --git a/shared-bindings/storage/__init__.c b/shared-bindings/storage/__init__.c
new file mode 100644
index 000000000..2b289a11f
--- /dev/null
+++ b/shared-bindings/storage/__init__.c
@@ -0,0 +1,117 @@
+/*
+ * This file is part of the Micro Python project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2013, 2014 Damien P. George
+ * Copyright (c) 2015 Josef Gajdusek
+ * Copyright (c) 2016 Scott Shawcroft for Adafruit Industries
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include <string.h>
+
+#include "extmod/vfs_fat.h"
+#include "py/obj.h"
+#include "py/objnamedtuple.h"
+#include "shared-bindings/storage/__init__.h"
+
+//| :mod:`storage` --- storage management
+//| ========================================================
+//|
+//| .. module:: storage
+//|   :synopsis: storage management
+//|   :platform: SAMD21
+//|
+//| The `storage` provides storage management functionality such as mounting and
+//| unmounting which is typically handled by the operating system hosting Python.
+//| CircuitPython does not have an OS, so this module provides this functionality
+//| directly. Its based on MicroPython's `uos` module but deliberately separates
+//| CPython compatible functionality (in `os`) from incompatible functionality
+//| (in `storage`).
+//|
+
+//| .. function:: mount(filesystem, mount_path, \*, readonly=False)
+//|
+//|   Mounts the given filesystem object at the given path.
+//|
+//|   This is the CircuitPython analog to the UNIX ``mount`` command.
+//|
+mp_obj_t storage_mount(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
+    enum { ARG_readonly };
+    static const mp_arg_t allowed_args[] = {
+        { MP_QSTR_readonly, MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_obj = mp_const_false} },
+    };
+
+    // parse args
+    mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
+    mp_arg_parse_all(n_args - 2, pos_args + 2, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
+
+    // get the mount point
+    const char *mnt_str = mp_obj_str_get_str(pos_args[1]);
+
+    // Make sure we're given an object we can mount.
+    // TODO(tannewt): Make sure we have all the methods we need to operating it
+    // as a file system.
+    mp_obj_t vfs_obj = pos_args[0];
+    mp_obj_t dest[2];
+    mp_load_method_maybe(vfs_obj, MP_QSTR_mount, dest);
+    if (dest[0] == MP_OBJ_NULL) {
+        mp_raise_ValueError("filesystem must provide mount method");
+    }
+
+    common_hal_storage_mount(vfs_obj, mnt_str, mp_obj_is_true(args[ARG_readonly].u_obj));
+
+    return mp_const_none;
+}
+MP_DEFINE_CONST_FUN_OBJ_KW(storage_mount_obj, 2, storage_mount);
+
+//| .. function:: umount(mount)
+//|
+//|   Unmounts the given filesystem object or if *mount* is a path, then unmount
+//|   the filesystem mounted at that location.
+//|
+//|   This is the CircuitPython analog to the UNIX ``umount`` command.
+//|
+mp_obj_t storage_umount(mp_obj_t mnt_in) {
+    if (MP_OBJ_IS_STR(mnt_in)) {
+        common_hal_storage_umount_path(mp_obj_str_get_str(mnt_in));
+    } else {
+        common_hal_storage_umount_object(mnt_in);
+    }
+
+    return mp_const_none;
+}
+MP_DEFINE_CONST_FUN_OBJ_1(storage_umount_obj, storage_umount);
+
+STATIC const mp_rom_map_elem_t storage_module_globals_table[] = {
+    { MP_OBJ_NEW_QSTR(MP_QSTR___name__), MP_OBJ_NEW_QSTR(MP_QSTR_storage) },
+
+    { MP_OBJ_NEW_QSTR(MP_QSTR_mount), MP_ROM_PTR(&storage_mount_obj) },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_umount), MP_ROM_PTR(&storage_umount_obj) },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_VfsFat), MP_ROM_PTR(&mp_fat_vfs_type) },
+};
+
+STATIC MP_DEFINE_CONST_DICT(storage_module_globals, storage_module_globals_table);
+
+const mp_obj_module_t storage_module = {
+    .base = { &mp_type_module },
+    .globals = (mp_obj_dict_t*)&storage_module_globals,
+};
diff --git a/shared-bindings/storage/__init__.h b/shared-bindings/storage/__init__.h
new file mode 100644
index 000000000..806bbc8b3
--- /dev/null
+++ b/shared-bindings/storage/__init__.h
@@ -0,0 +1,37 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2017 Scott Shawcroft for Adafruit Industries
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#ifndef __MICROPY_INCLUDED_SHARED_BINDINGS_STORAGE___INIT___H__
+#define __MICROPY_INCLUDED_SHARED_BINDINGS_STORAGE___INIT___H__
+
+#include <stdint.h>
+#include <stdbool.h>
+
+void common_hal_storage_mount(mp_obj_t vfs_obj, const char* path, bool readonly);
+void common_hal_storage_umount_path(const char* path);
+void common_hal_storage_umount_object(mp_obj_t vfs_obj);
+
+#endif  // __MICROPY_INCLUDED_SHARED_BINDINGS_STORAGE___INIT___H__
diff --git a/shared-module/os/__init__.c b/shared-module/os/__init__.c
new file mode 100644
index 000000000..b628d4971
--- /dev/null
+++ b/shared-module/os/__init__.c
@@ -0,0 +1,188 @@
+/*
+ * This file is part of the Micro Python project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2013, 2014 Damien P. George
+ * Copyright (c) 2015 Josef Gajdusek
+ * Copyright (c) 2017 Scott Shawcroft for Adafruit Industries
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include <string.h>
+
+#include "extmod/vfs.h"
+#include "py/mperrno.h"
+#include "py/mpstate.h"
+#include "py/obj.h"
+#include "py/objstr.h"
+#include "py/runtime.h"
+#include "shared-bindings/os/__init__.h"
+
+// This provides all VFS related OS functions so that ports can share the code
+// as needed. It does not provide uname.
+
+// Version of mp_vfs_lookup_path that takes and returns uPy string objects.
+STATIC mp_vfs_mount_t *lookup_path(const char* path, mp_obj_t *path_out) {
+    const char *p_out;
+    mp_vfs_mount_t *vfs = mp_vfs_lookup_path(path, &p_out);
+    if (vfs != MP_VFS_NONE && vfs != MP_VFS_ROOT) {
+        *path_out = mp_obj_new_str_of_type(mp_obj_get_type(path),
+            (const byte*)p_out, strlen(p_out));
+    }
+    return vfs;
+}
+
+STATIC mp_obj_t mp_vfs_proxy_call(mp_vfs_mount_t *vfs, qstr meth_name, size_t n_args, const mp_obj_t *args) {
+    if (vfs == MP_VFS_NONE) {
+        // mount point not found
+        mp_raise_OSError(MP_ENODEV);
+    }
+    if (vfs == MP_VFS_ROOT) {
+        // can't do operation on root dir
+        mp_raise_OSError(MP_EPERM);
+    }
+    mp_obj_t meth[n_args + 2];
+    mp_load_method(vfs->obj, meth_name, meth);
+    if (args != NULL) {
+        memcpy(meth + 2, args, n_args * sizeof(*args));
+    }
+    return mp_call_method_n_kw(n_args, 0, meth);
+}
+
+void common_hal_os_chdir(const char* path) {
+    mp_obj_t path_out;
+    mp_vfs_mount_t *vfs = lookup_path(path, &path_out);
+    MP_STATE_VM(vfs_cur) = vfs;
+    if (vfs == MP_VFS_ROOT) {
+        // If we change to the root dir and a VFS is mounted at the root then
+        // we must change that VFS's current dir to the root dir so that any
+        // subsequent relative paths begin at the root of that VFS.
+        for (vfs = MP_STATE_VM(vfs_mount_table); vfs != NULL; vfs = vfs->next) {
+            if (vfs->len == 1) {
+                mp_obj_t root = mp_obj_new_str("/", 1, false);
+                mp_vfs_proxy_call(vfs, MP_QSTR_chdir, 1, &root);
+                break;
+            }
+        }
+    } else {
+        mp_vfs_proxy_call(vfs, MP_QSTR_chdir, 1, &path_out);
+    }
+}
+
+mp_obj_t common_hal_os_getcwd(void) {
+    return mp_vfs_getcwd();
+}
+
+mp_obj_t common_hal_os_listdir(const char* path) {
+    mp_obj_t path_out;
+    mp_vfs_mount_t *vfs = lookup_path(path, &path_out);
+
+    if (vfs == MP_VFS_ROOT) {
+        // list the root directory
+        mp_vfs_ilistdir_it_t *iter = m_new_obj(mp_vfs_ilistdir_it_t);
+        iter->base.type = &mp_type_polymorph_iter;
+        iter->iternext = mp_vfs_ilistdir_it_iternext;
+        iter->cur.vfs = MP_STATE_VM(vfs_mount_table);
+        iter->is_str = mp_obj_get_type(path) == &mp_type_str;
+        iter->is_iter = false;
+        return MP_OBJ_FROM_PTR(iter);
+    }
+
+    return mp_vfs_proxy_call(vfs, MP_QSTR_ilistdir, 1, &path_out);
+}
+
+void common_hal_os_mkdir(const char* path) {
+    mp_obj_t path_out;
+    mp_vfs_mount_t *vfs = lookup_path(path, &path_out);
+    if (vfs == MP_VFS_ROOT || (vfs != MP_VFS_NONE && !strcmp(mp_obj_str_get_str(path_out), "/"))) {
+        mp_raise_OSError(MP_EEXIST);
+    }
+    mp_vfs_proxy_call(vfs, MP_QSTR_mkdir, 1, &path_out);
+}
+
+void common_hal_os_remove(const char* path) {
+    mp_obj_t path_out;
+    mp_vfs_mount_t *vfs = lookup_path(path, &path_out);
+    mp_vfs_proxy_call(vfs, MP_QSTR_remove, 1, &path_out);
+}
+
+void common_hal_os_rename(const char* old_path, const char* new_path) {
+    mp_obj_t args[2];
+    mp_vfs_mount_t *old_vfs = lookup_path(old_path, &args[0]);
+    mp_vfs_mount_t *new_vfs = lookup_path(new_path, &args[1]);
+    if (old_vfs != new_vfs) {
+        // can't rename across filesystems
+        mp_raise_OSError(MP_EPERM);
+    }
+    mp_vfs_proxy_call(old_vfs, MP_QSTR_rename, 2, args);
+}
+
+void common_hal_os_rmdir(const char* path) {
+    mp_obj_t path_out;
+    mp_vfs_mount_t *vfs = lookup_path(path, &path_out);
+    mp_vfs_proxy_call(vfs, MP_QSTR_rmdir, 1, &path_out);
+}
+
+mp_obj_t common_hal_os_stat(const char* path) {
+    mp_obj_t path_out;
+    mp_vfs_mount_t *vfs = lookup_path(path, &path_out);
+    if (vfs == MP_VFS_ROOT) {
+        mp_obj_tuple_t *t = MP_OBJ_TO_PTR(mp_obj_new_tuple(10, NULL));
+        t->items[0] = MP_OBJ_NEW_SMALL_INT(MP_S_IFDIR); // st_mode
+        for (int i = 1; i <= 9; ++i) {
+            t->items[i] = MP_OBJ_NEW_SMALL_INT(0); // dev, nlink, uid, gid, size, atime, mtime, ctime
+        }
+        return MP_OBJ_FROM_PTR(t);
+    }
+    return mp_vfs_proxy_call(vfs, MP_QSTR_stat, 1, &path_out);
+}
+
+mp_obj_t common_hal_os_statvfs(const char* path) {
+    mp_obj_t path_out;
+    mp_vfs_mount_t *vfs = lookup_path(path, &path_out);
+    if (vfs == MP_VFS_ROOT) {
+        // statvfs called on the root directory, see if there's anything mounted there
+        for (vfs = MP_STATE_VM(vfs_mount_table); vfs != NULL; vfs = vfs->next) {
+            if (vfs->len == 1) {
+                break;
+            }
+        }
+
+        // If there's nothing mounted at root then return a mostly-empty tuple
+        if (vfs == NULL) {
+            mp_obj_tuple_t *t = MP_OBJ_TO_PTR(mp_obj_new_tuple(10, NULL));
+
+            // fill in: bsize, frsize, blocks, bfree, bavail, files, ffree, favail, flags
+            for (int i = 0; i <= 8; ++i) {
+                t->items[i] = MP_OBJ_NEW_SMALL_INT(0);
+            }
+
+            // Put something sensible in f_namemax
+            t->items[9] = MP_OBJ_NEW_SMALL_INT(MICROPY_ALLOC_PATH_MAX);
+
+            return MP_OBJ_FROM_PTR(t);
+        }
+
+        // VFS mounted at root so delegate the call to it
+        path_out = MP_OBJ_NEW_QSTR(MP_QSTR__slash_);
+    }
+    return mp_vfs_proxy_call(vfs, MP_QSTR_statvfs, 1, &path_out);
+}
diff --git a/shared-module/storage/__init__.c b/shared-module/storage/__init__.c
new file mode 100644
index 000000000..582b91a5b
--- /dev/null
+++ b/shared-module/storage/__init__.c
@@ -0,0 +1,133 @@
+/*
+ * This file is part of the Micro Python project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2013, 2014 Damien P. George
+ * Copyright (c) 2015 Josef Gajdusek
+ * Copyright (c) 2017 Scott Shawcroft for Adafruit Industries
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include <string.h>
+
+#include "extmod/vfs.h"
+#include "py/mperrno.h"
+#include "py/obj.h"
+#include "py/runtime.h"
+#include "shared-bindings/storage/__init__.h"
+
+STATIC mp_obj_t mp_vfs_proxy_call(mp_vfs_mount_t *vfs, qstr meth_name, size_t n_args, const mp_obj_t *args) {
+    if (vfs == MP_VFS_NONE) {
+        // mount point not found
+        mp_raise_OSError(MP_ENODEV);
+    }
+    if (vfs == MP_VFS_ROOT) {
+        // can't do operation on root dir
+        mp_raise_OSError(MP_EPERM);
+    }
+    mp_obj_t meth[n_args + 2];
+    mp_load_method(vfs->obj, meth_name, meth);
+    if (args != NULL) {
+        memcpy(meth + 2, args, n_args * sizeof(*args));
+    }
+    return mp_call_method_n_kw(n_args, 0, meth);
+}
+
+void common_hal_storage_mount(mp_obj_t vfs_obj, const char* mount_path, bool readonly) {
+    // create new object
+    mp_vfs_mount_t *vfs = m_new_obj(mp_vfs_mount_t);
+    vfs->str = mount_path;
+    vfs->len = strlen(mount_path);
+    vfs->obj = vfs_obj;
+    vfs->next = NULL;
+
+    mp_obj_t args[2];
+    args[0] = readonly ? mp_const_true : mp_const_false;
+    args[1] = mp_const_false; // Don't make the file system automatically when mounting.
+
+    // call the underlying object to do any mounting operation
+    mp_vfs_proxy_call(vfs, MP_QSTR_mount, 2, (mp_obj_t*)&args);
+
+    // check that the destination mount point is unused
+    const char *path_out;
+    mp_vfs_mount_t *existing_mount = mp_vfs_lookup_path(mount_path, &path_out);
+    if (existing_mount != MP_VFS_NONE && existing_mount != MP_VFS_ROOT) {
+        if (vfs->len != 1 && existing_mount->len == 1) {
+            // if root dir is mounted, still allow to mount something within a subdir of root
+        } else {
+            // mount point in use
+            mp_raise_OSError(MP_EPERM);
+        }
+    }
+
+    // insert the vfs into the mount table
+    mp_vfs_mount_t **vfsp = &MP_STATE_VM(vfs_mount_table);
+    while (*vfsp != NULL) {
+        if ((*vfsp)->len == 1) {
+            // make sure anything mounted at the root stays at the end of the list
+            vfs->next = *vfsp;
+            break;
+        }
+        vfsp = &(*vfsp)->next;
+    }
+    *vfsp = vfs;
+}
+
+void common_hal_storage_umount_object(mp_obj_t vfs_obj) {
+    // remove vfs from the mount table
+    mp_vfs_mount_t *vfs = NULL;
+    for (mp_vfs_mount_t **vfsp = &MP_STATE_VM(vfs_mount_table); *vfsp != NULL; vfsp = &(*vfsp)->next) {
+        if ((*vfsp)->obj == vfs_obj) {
+            vfs = *vfsp;
+            *vfsp = (*vfsp)->next;
+            break;
+        }
+    }
+
+    if (vfs == NULL) {
+        mp_raise_OSError(MP_EINVAL);
+    }
+
+    // if we unmounted the current device then set current to root
+    if (MP_STATE_VM(vfs_cur) == vfs) {
+        MP_STATE_VM(vfs_cur) = MP_VFS_ROOT;
+    }
+
+    // call the underlying object to do any unmounting operation
+    mp_vfs_proxy_call(vfs, MP_QSTR_umount, 0, NULL);
+}
+
+void common_hal_storage_umount_path(const char* mount_path) {
+    // remove vfs from the mount table
+    mp_obj_t *vfs_obj = NULL;
+    for (mp_vfs_mount_t **vfsp = &MP_STATE_VM(vfs_mount_table); *vfsp != NULL; vfsp = &(*vfsp)->next) {
+        if (strcmp(mount_path, (*vfsp)->str) == 0) {
+            vfs_obj = (*vfsp)->obj;
+            break;
+        }
+    }
+
+    if (vfs_obj == NULL) {
+        mp_raise_OSError(MP_EINVAL);
+    }
+
+    common_hal_storage_umount_object(vfs_obj);
+}